1. Field of the Invention
The present invention relates generally to a power transmission mechanism for a compression of a vehicle. In particular, the present invention is directed to a power transmission mechanism having a torque limiter.
2. Description of Related Art
Known compressors for a vehicle are driven by an engine of the vehicle via a power transmission mechanism. Known power transmission mechanisms, such as the power transmission mechanism described in U.S. Pat. No. 6,425,837 B1, have a torque limiter which prevents excessive torque generated by a seizure of the compressor from being transmitted to the engine of the vehicle. Specifically, such known power transmission mechanisms include a first rotation member and a second rotation member, and each rotation member includes accommodation portions. The first rotation member is fixed to a shaft of the known compressor, and the second rotation member is arranged, so as to rotate in accordance with a rotation of the engine of the vehicle.
Such known power transmission mechanisms, also include a plurality of balls coupled to the first rotation member and the second rotation member. During operation, a first portion of each of the balls is accommodated within the accommodation portion of the first rotation member, and a second portion of each of the balls is accommodated within the accommodation portion of the second rotation member, such that the each of the balls substantially couple the first rotation member to the second rotation member. Thus, during operation, the rotational motion of the second rotation member is transmitted to the first rotation member via the balls.
If a compressor containing such a power transmission mechanism seizes up, the first rotation member does not rotate smoothly, and the second rotation member pushes the balls toward the first rotation member. Consequently, the second rotation member uncouples from the first rotation member, such that excessive torque generated by the seizure of the compressor is not transmitted to the engine of the vehicle.
In known compressors, in order to maintain reliable operation of the balls, an area surrounding the balls may be filled with a rust inhibitor or a lubricant, e.g., a grease, or both. In order to ensure that the balls function as a torque limiter, the area is sealed off, such that foreign objects do not enter the area, and the rust inhibitor and the lubricant do not leak out of the area. Nevertheless, when such known compressors are turned off, a thrust occurs which forces the shaft to move inwardly. When the shaft moves inward, components coupled to the shaft are displaced, which may break the seal.